1 //===- InstrumentationMap.cpp - XRay Instrumentation Map ------------------===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 // 9 // Implementation of the InstrumentationMap type for XRay sleds. 10 // 11 //===----------------------------------------------------------------------===// 12 13 #include "llvm/XRay/InstrumentationMap.h" 14 #include "llvm/ADT/DenseMap.h" 15 #include "llvm/ADT/None.h" 16 #include "llvm/ADT/STLExtras.h" 17 #include "llvm/ADT/StringRef.h" 18 #include "llvm/ADT/Triple.h" 19 #include "llvm/ADT/Twine.h" 20 #include "llvm/Object/Binary.h" 21 #include "llvm/Object/ELFObjectFile.h" 22 #include "llvm/Object/ObjectFile.h" 23 #include "llvm/Object/RelocationResolver.h" 24 #include "llvm/Support/DataExtractor.h" 25 #include "llvm/Support/Error.h" 26 #include "llvm/Support/FileSystem.h" 27 #include "llvm/Support/YAMLTraits.h" 28 #include <algorithm> 29 #include <cstddef> 30 #include <cstdint> 31 #include <system_error> 32 #include <vector> 33 34 using namespace llvm; 35 using namespace xray; 36 37 Optional<int32_t> InstrumentationMap::getFunctionId(uint64_t Addr) const { 38 auto I = FunctionIds.find(Addr); 39 if (I != FunctionIds.end()) 40 return I->second; 41 return None; 42 } 43 44 Optional<uint64_t> InstrumentationMap::getFunctionAddr(int32_t FuncId) const { 45 auto I = FunctionAddresses.find(FuncId); 46 if (I != FunctionAddresses.end()) 47 return I->second; 48 return None; 49 } 50 51 using RelocMap = DenseMap<uint64_t, uint64_t>; 52 53 static Error 54 loadObj(StringRef Filename, object::OwningBinary<object::ObjectFile> &ObjFile, 55 InstrumentationMap::SledContainer &Sleds, 56 InstrumentationMap::FunctionAddressMap &FunctionAddresses, 57 InstrumentationMap::FunctionAddressReverseMap &FunctionIds) { 58 InstrumentationMap Map; 59 60 // Find the section named "xray_instr_map". 61 if ((!ObjFile.getBinary()->isELF() && !ObjFile.getBinary()->isMachO()) || 62 !(ObjFile.getBinary()->getArch() == Triple::x86_64 || 63 ObjFile.getBinary()->getArch() == Triple::ppc64le || 64 ObjFile.getBinary()->getArch() == Triple::arm || 65 ObjFile.getBinary()->getArch() == Triple::aarch64)) 66 return make_error<StringError>( 67 "File format not supported (only does ELF and Mach-O little endian " 68 "64-bit).", 69 std::make_error_code(std::errc::not_supported)); 70 71 StringRef Contents = ""; 72 const auto &Sections = ObjFile.getBinary()->sections(); 73 uint64_t Address = 0; 74 auto I = llvm::find_if(Sections, [&](object::SectionRef Section) { 75 Expected<StringRef> NameOrErr = Section.getName(); 76 if (NameOrErr) { 77 Address = Section.getAddress(); 78 return *NameOrErr == "xray_instr_map"; 79 } 80 consumeError(NameOrErr.takeError()); 81 return false; 82 }); 83 84 if (I == Sections.end()) 85 return make_error<StringError>( 86 "Failed to find XRay instrumentation map.", 87 std::make_error_code(std::errc::executable_format_error)); 88 89 if (Expected<StringRef> E = I->getContents()) 90 Contents = *E; 91 else 92 return E.takeError(); 93 94 RelocMap Relocs; 95 if (ObjFile.getBinary()->isELF()) { 96 uint32_t RelativeRelocation = [](object::ObjectFile *ObjFile) { 97 if (const auto *ELFObj = dyn_cast<object::ELF32LEObjectFile>(ObjFile)) 98 return ELFObj->getELFFile()->getRelativeRelocationType(); 99 else if (const auto *ELFObj = 100 dyn_cast<object::ELF32BEObjectFile>(ObjFile)) 101 return ELFObj->getELFFile()->getRelativeRelocationType(); 102 else if (const auto *ELFObj = 103 dyn_cast<object::ELF64LEObjectFile>(ObjFile)) 104 return ELFObj->getELFFile()->getRelativeRelocationType(); 105 else if (const auto *ELFObj = 106 dyn_cast<object::ELF64BEObjectFile>(ObjFile)) 107 return ELFObj->getELFFile()->getRelativeRelocationType(); 108 else 109 return static_cast<uint32_t>(0); 110 }(ObjFile.getBinary()); 111 112 bool (*SupportsRelocation)(uint64_t); 113 object::RelocationResolver Resolver; 114 std::tie(SupportsRelocation, Resolver) = 115 object::getRelocationResolver(*ObjFile.getBinary()); 116 117 for (const object::SectionRef &Section : Sections) { 118 for (const object::RelocationRef &Reloc : Section.relocations()) { 119 if (ObjFile.getBinary()->getArch() == Triple::arm) { 120 if (SupportsRelocation && SupportsRelocation(Reloc.getType())) { 121 Expected<uint64_t> ValueOrErr = Reloc.getSymbol()->getValue(); 122 if (!ValueOrErr) 123 return ValueOrErr.takeError(); 124 Relocs.insert({Reloc.getOffset(), Resolver(Reloc, *ValueOrErr, 0)}); 125 } 126 } else if (SupportsRelocation && SupportsRelocation(Reloc.getType())) { 127 auto AddendOrErr = object::ELFRelocationRef(Reloc).getAddend(); 128 auto A = AddendOrErr ? *AddendOrErr : 0; 129 Expected<uint64_t> ValueOrErr = Reloc.getSymbol()->getValue(); 130 if (!ValueOrErr) 131 // TODO: Test this error. 132 return ValueOrErr.takeError(); 133 Relocs.insert({Reloc.getOffset(), Resolver(Reloc, *ValueOrErr, A)}); 134 } else if (Reloc.getType() == RelativeRelocation) { 135 if (auto AddendOrErr = object::ELFRelocationRef(Reloc).getAddend()) 136 Relocs.insert({Reloc.getOffset(), *AddendOrErr}); 137 } 138 } 139 } 140 } 141 142 // Copy the instrumentation map data into the Sleds data structure. 143 auto C = Contents.bytes_begin(); 144 bool Is32Bit = ObjFile.getBinary()->makeTriple().isArch32Bit(); 145 size_t ELFSledEntrySize = Is32Bit ? 16 : 32; 146 147 if ((C - Contents.bytes_end()) % ELFSledEntrySize != 0) 148 return make_error<StringError>( 149 Twine("Instrumentation map entries not evenly divisible by size of " 150 "an XRay sled entry."), 151 std::make_error_code(std::errc::executable_format_error)); 152 153 auto RelocateOrElse = [&](uint64_t Offset, uint64_t Address) { 154 if (!Address) { 155 uint64_t A = I->getAddress() + C - Contents.bytes_begin() + Offset; 156 RelocMap::const_iterator R = Relocs.find(A); 157 if (R != Relocs.end()) 158 return R->second; 159 } 160 return Address; 161 }; 162 163 const int WordSize = Is32Bit ? 4 : 8; 164 int32_t FuncId = 1; 165 uint64_t CurFn = 0; 166 for (; C != Contents.bytes_end(); C += ELFSledEntrySize) { 167 DataExtractor Extractor( 168 StringRef(reinterpret_cast<const char *>(C), ELFSledEntrySize), true, 169 8); 170 Sleds.push_back({}); 171 auto &Entry = Sleds.back(); 172 uint64_t OffsetPtr = 0; 173 uint64_t AddrOff = OffsetPtr; 174 if (Is32Bit) 175 Entry.Address = RelocateOrElse(AddrOff, Extractor.getU32(&OffsetPtr)); 176 else 177 Entry.Address = RelocateOrElse(AddrOff, Extractor.getU64(&OffsetPtr)); 178 uint64_t FuncOff = OffsetPtr; 179 if (Is32Bit) 180 Entry.Function = RelocateOrElse(FuncOff, Extractor.getU32(&OffsetPtr)); 181 else 182 Entry.Function = RelocateOrElse(FuncOff, Extractor.getU64(&OffsetPtr)); 183 auto Kind = Extractor.getU8(&OffsetPtr); 184 static constexpr SledEntry::FunctionKinds Kinds[] = { 185 SledEntry::FunctionKinds::ENTRY, SledEntry::FunctionKinds::EXIT, 186 SledEntry::FunctionKinds::TAIL, 187 SledEntry::FunctionKinds::LOG_ARGS_ENTER, 188 SledEntry::FunctionKinds::CUSTOM_EVENT}; 189 if (Kind >= sizeof(Kinds)) 190 return errorCodeToError( 191 std::make_error_code(std::errc::executable_format_error)); 192 Entry.Kind = Kinds[Kind]; 193 Entry.AlwaysInstrument = Extractor.getU8(&OffsetPtr) != 0; 194 Entry.Version = Extractor.getU8(&OffsetPtr); 195 if (Entry.Version >= 2) { 196 Entry.Address += C - Contents.bytes_begin() + Address; 197 Entry.Function += C - Contents.bytes_begin() + WordSize + Address; 198 } 199 200 // We do replicate the function id generation scheme implemented in the 201 // XRay runtime. 202 // FIXME: Figure out how to keep this consistent with the XRay runtime. 203 if (CurFn == 0) { 204 CurFn = Entry.Function; 205 FunctionAddresses[FuncId] = Entry.Function; 206 FunctionIds[Entry.Function] = FuncId; 207 } 208 if (Entry.Function != CurFn) { 209 ++FuncId; 210 CurFn = Entry.Function; 211 FunctionAddresses[FuncId] = Entry.Function; 212 FunctionIds[Entry.Function] = FuncId; 213 } 214 } 215 return Error::success(); 216 } 217 218 static Error 219 loadYAML(sys::fs::file_t Fd, size_t FileSize, StringRef Filename, 220 InstrumentationMap::SledContainer &Sleds, 221 InstrumentationMap::FunctionAddressMap &FunctionAddresses, 222 InstrumentationMap::FunctionAddressReverseMap &FunctionIds) { 223 std::error_code EC; 224 sys::fs::mapped_file_region MappedFile( 225 Fd, sys::fs::mapped_file_region::mapmode::readonly, FileSize, 0, EC); 226 sys::fs::closeFile(Fd); 227 if (EC) 228 return make_error<StringError>( 229 Twine("Failed memory-mapping file '") + Filename + "'.", EC); 230 231 std::vector<YAMLXRaySledEntry> YAMLSleds; 232 yaml::Input In(StringRef(MappedFile.data(), MappedFile.size())); 233 In >> YAMLSleds; 234 if (In.error()) 235 return make_error<StringError>( 236 Twine("Failed loading YAML document from '") + Filename + "'.", 237 In.error()); 238 239 Sleds.reserve(YAMLSleds.size()); 240 for (const auto &Y : YAMLSleds) { 241 FunctionAddresses[Y.FuncId] = Y.Function; 242 FunctionIds[Y.Function] = Y.FuncId; 243 Sleds.push_back(SledEntry{Y.Address, Y.Function, Y.Kind, Y.AlwaysInstrument, 244 Y.Version}); 245 } 246 return Error::success(); 247 } 248 249 // FIXME: Create error types that encapsulate a bit more information than what 250 // StringError instances contain. 251 Expected<InstrumentationMap> 252 llvm::xray::loadInstrumentationMap(StringRef Filename) { 253 // At this point we assume the file is an object file -- and if that doesn't 254 // work, we treat it as YAML. 255 // FIXME: Extend to support non-ELF and non-x86_64 binaries. 256 257 InstrumentationMap Map; 258 auto ObjectFileOrError = object::ObjectFile::createObjectFile(Filename); 259 if (!ObjectFileOrError) { 260 auto E = ObjectFileOrError.takeError(); 261 // We try to load it as YAML if the ELF load didn't work. 262 Expected<sys::fs::file_t> FdOrErr = 263 sys::fs::openNativeFileForRead(Filename); 264 if (!FdOrErr) { 265 // Report the ELF load error if YAML failed. 266 consumeError(FdOrErr.takeError()); 267 return std::move(E); 268 } 269 270 uint64_t FileSize; 271 if (sys::fs::file_size(Filename, FileSize)) 272 return std::move(E); 273 274 // If the file is empty, we return the original error. 275 if (FileSize == 0) 276 return std::move(E); 277 278 // From this point on the errors will be only for the YAML parts, so we 279 // consume the errors at this point. 280 consumeError(std::move(E)); 281 if (auto E = loadYAML(*FdOrErr, FileSize, Filename, Map.Sleds, 282 Map.FunctionAddresses, Map.FunctionIds)) 283 return std::move(E); 284 } else if (auto E = loadObj(Filename, *ObjectFileOrError, Map.Sleds, 285 Map.FunctionAddresses, Map.FunctionIds)) { 286 return std::move(E); 287 } 288 return Map; 289 } 290